It is common practice in hospitals and other medical environments to sterilize medical instruments with steam or other sterilizing gases. Sterilization containers provide a convenient enclosure in which the sterilization can be performed. These containers normally have housings with a bottom and sidewalls, removable lids, ports for the passage of sterilization gases and condensate, and a sealing mechanism to prevent contaminants from entering the container after sterilizing. The containers may have one or more inlet ports in the lid and one or more outlet ports in the bottom. A filter unit, having anyone of a number of commercially available filter mediums which allow the passage of air, steam and other sterilization gases but which prevent, retard or inhibit, the passage of contaminants such as dirt, dust and bacteria, is normally disposed in each of the ports. The filter mediums are most commonly hydrophobic like, such that moisture will not pass therethrough unless a sufficient pressure difference is created between the inside of the medical sterilization container and the surrounding sterilizing chamber.
During steam sterilization processes, steam is forced through the various ports in the container to sterilize microorganisms such as bacteria. During this process, water condensate is normally left behind. Although the bacteria inside the container should be substantially eliminated through the sterilization process, medical technicians are trained to regard moisture as a breeding place for bacteria, and thus condensate tends to cause technician acceptance problems as well as providing an actual possible breeding ground for bacteria. In addition, the condensate increases the possibility for rusting and other deterioration of the medical instruments in the container.
Steam sterilization units, whether they be gravity steam, pulsating, pressure steam or alternating vacuum and pressure or the like, all normally have a drying cycle. During the drying cycle, the pressure of the chamber surrounding the medical sterilization container is normally decreased in order to lower the boiling point of the moisture.
Presently available filter units normally consist of a frame which supports a filter element across the aperture of the corresponding port. One or more cross-members may be provided across the frame for strength and rigidity. These cross-members, while strengthening the filter unit, can reduce the efficiency of the drying cycle. This is due to the fact that the cross-members in the presently available filter units have been interposed between the interior of the medical sterilization container and the filter medium when the filter unit is seated in a filter port. The cross-members thereby provide an internal surface area which can impede condensate and steam which is exiting the port of the container. Further, the cross-members provide an undesirable area on which steam can recondense during the drying process, further impeding drainage of condensate from the container. The overall result is an unnecessarily lengthy drying process.
Thus, the need has arisen for a filter unit which enables the unimpeded flow of moisture out of a medical instrument sterilization container port during a drying cycle. This will allow faster and more efficient sterilization while reducing the chances of rejection of the sterilized instruments by inspecting medical technicians. Such a filter unit, however, would retain the necessary strength and rigidity to keep the filter unit firmly seated in the associated filter port.